Clamp based methods and apparatus for forming lesions in tissue and confirming whether a therapeutic lesion has been formed

ABSTRACT

Surgical systems, devices and methods including one or more tissue stimulation elements that, in some instances, may also be used for sensing purposes. Some of the surgical devices also include a tissue coagulation element.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.10/727,144, filed Dec. 2, 2003, now issued as U.S. Pat. No. 8,002,770,entitled ‘CLAMP BASED METHODS AND APPARATUS FOR FORMING LESIONS INTISSUE AND CONFIRMING WHETHER A THERAPEUTIC LESION HAS BEEN FORMED,” theentire disclosure of which is incorporated herein by reference for allpurposes.

BACKGROUND OF THE INVENTIONS

1. Field of Inventions

The present inventions relate generally to surgical devices for formingtherapeutic lesions.

2. Description of the Related Art

There are many instances where therapeutic elements must be insertedinto the body. One instance involves the formation of therapeuticlesions to the treat cardiac conditions such as atrial fibrillation,atrial flutter and arrhythmia. Therapeutic lesions may also be used totreat conditions in other regions of the body including, but not limitedto, the prostate, liver, brain, gall bladder, uterus and other solidorgans. Typically, the lesions are formed by ablating tissue with one ormore electrodes. Electromagnetic radio frequency (“RF”) energy appliedby the electrode heats, and eventually kills (i.e. “ablates”), thetissue to form a lesion. During the ablation of soft tissue (i.e. tissueother than blood, bone and connective tissue), tissue coagulation occursand it is the coagulation that kills the tissue. Thus, references to theablation of soft tissue are necessarily references to soft tissuecoagulation. “Tissue coagulation” is the process of cross-linkingproteins in tissue to cause the tissue to jell. In soft tissue, it isthe fluid within the tissue cell membranes that jells to kill the cells,thereby killing the tissue.

Depending on the procedure, a variety of different electrophysiologydevices may be used to position one or more coagulation electrodes atthe target location. Each electrode is connected to a power supply andcontrol apparatus and, in some instances, the power to the electrodes iscontrolled on an electrode-by-electrode basis. Examples ofelectrophysiology devices include catheters and surgical devices such assurgical probes and clamps. Catheters are relatively long, flexibledevices that are configured to travel through a vein or artery until thecoagulation electrodes carried on their distal portions reach the targettissue. The electrodes on the distal portions of surgical devices are,on the other hand, typically placed directly in contact with thetargeted tissue area by a physician during a surgical procedure, such asopen heart surgery, where access can be obtained by way of athoracotomy, median stemotomy, or thoracostomy.

Catheters used to create lesions typically include a relatively long andrelatively flexible body that has one or more coagulation electrodes onits distal portion. The portion of the catheter body that is insertedinto the patient is typically from 23 to 55 inches in length and theremay be another 8 to 15 inches, including a handle, outside the patient.The proximal end of the catheter body is connected to the handle whichincludes steering controls. The length and flexibility of the catheterbody allow the catheter to be inserted into a main vein or artery(typically the femoral artery), directed into the interior of the heart,and then manipulated such that the electrode contacts the tissue that isto be ablated. Fluoroscopic imaging is used to provide the physicianwith a visual indication of the location of the catheter. Exemplarycatheters are disclosed in U.S. Pat. No. 5,582,609.

Surgical probes used to create lesions often include a handle, arelatively short shaft that is from 4 inches to 18 inches in length andeither rigid or relatively stiff, and a distal section that is from 1inch to 10 inches in length and either malleable or somewhat flexible.One or more coagulation electrodes are carried by the distal section.Surgical probes are used in epicardial and endocardial procedures,including open heart procedures and minimally invasive procedures whereaccess to the heart is obtained via a thoracotomy, thoracostomy ormedian stemotomy. Exemplary surgical probes are disclosed in U.S. Pat.No. 6,142,994.

Clamps, which have a pair of opposable clamp members that may be used tohold a bodily structure or a portion thereof, are another example of asurgical device that has been used to create lesions. Examples of clampswhich carry coagulation electrodes are disclosed in U.S. Pat. No.6,142,994. Such clamps are particularly useful when the physicianintends to position electrodes on opposite sides of a body structure ina bipolar arrangement.

The inventor herein has determined that conventional apparatus andmethods for forming therapeutic lesions are susceptible to improvement.For example, inventor herein has determined that conventional methodsand apparatus for confirming whether a therapeutic lesion has beenproperly formed during surgical procedures are susceptible ofimprovement. The inventor herein has also determined that conventionalmethods and apparatus for securing stimulation and sensing electrodes totissue during surgical procedures are susceptible of improvement.

SUMMARY OF THE INVENTIONS

Surgical devices in accordance with some embodiments of the presentinventions include a tissue stimulation element that, in some instances,may also be used for sensing purposes. Some of the surgical devices alsoinclude a tissue coagulation element. The present surgical deviceprovide a number of advantages over conventional surgical devices. Forexample, the some of the surgical devices may be used to form lesionsand also used to determine whether or not a therapeutic lesion has beenformed. The surgical devices may also be used to bring stimulation andsensing elements into contact with tissue in a manner that is superiorto conventional methods.

The above described and many other features and attendant advantages ofthe present inventions will become apparent as the inventions becomebetter understood by reference to the following detailed descriptionwhen considered in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Detailed description of preferred embodiments of the inventions will bemade with reference to the accompanying drawings.

FIG. 1 is a perspective view of a surgical system in accordance with apreferred embodiment of a present invention.

FIG. 2 is a plan view of a surgical probe in accordance with a preferredembodiment of a present invention.

FIG. 3 is a section view taken along line 3-3 in FIG. 2.

FIG. 4 is a section view taken along line 4-4 in FIG. 2.

FIG. 5 is a section view taken along line 5-5 in FIG. 2.

FIG. 6 is an end view of the surgical probe illustrated in FIG. 2.

FIG. 6A is a perspective view of a surgical system in accordance with apreferred embodiment of a present invention.

FIG. 6B is a plan view of a portion of a surgical probe in accordancewith a preferred embodiment of a present invention.

FIG. 7 is a perspective view of a surgical system in accordance with apreferred embodiment of a present invention.

FIG. 8 is a top view of a suction device in accordance with a preferredembodiment of a present invention.

FIG. 9 is a side view of the suction device illustrated in FIG. 8.

FIG. 10 is a bottom view of the suction device illustrated in FIG. 8.

FIG. 11 is a partial section view taken along line 11-11 in FIG. 9.

FIG. 12 is a section view taken along line 12-12 in FIG. 10.

FIG. 13 is a section view taken along line 13-13 in FIG. 10.

FIG. 14 is a bottom view of showing a portion of the surgical systemillustrated in FIG. 7.

FIG. 15 is a partial section view taken along line 15-15 in FIG. 14.

FIG. 16 is a perspective view of a surgical system in accordance with apreferred embodiment of a present invention.

FIG. 17 is a plan view of a tissue coagulation and stimulation assemblyin accordance with a preferred embodiment of a present invention.

FIG. 18 is a section view taken along line 18-18 in FIG. 17.

FIG. 19 is a section view taken along line 19-19 in FIG. 17.

FIG. 20 is an enlarged view of a portion of the tissue coagulation andstimulation assembly illustrated in FIG. 17.

FIG. 21 is a section view taken along line 21-21 in FIG. 20.

FIG. 22 is a plan view of a clamp in accordance with a preferredembodiment of a present invention.

FIG. 23 is a section view taken along line 23-23 in FIG. 22.

FIG. 24 is a top view of a portion of the clamp illustrated in FIG. 22.

FIG. 24A is a side view of a portion of a tissue coagulation andstimulation assembly in accordance with one embodiment of a presentinvention.

FIG. 24B is a side view of a portion of a tissue coagulation andstimulation assembly in accordance with one embodiment of a presentinvention.

FIG. 24C is an enlarged view of a portion of a tissue coagulation andstimulation assembly in accordance with one embodiment of a presentinvention.

FIG. 24D is a section view taken along line 24D-24D in FIG. 24C.

FIG. 24E is a section view taken along line 24E-24E in FIG. 24C.

FIG. 24F is an enlarged view of a portion of the tissue coagulation andstimulation assembly illustrated in FIG. 24C.

FIG. 24G is partial section view taken along line 24G-24G in FIG. 24F.

FIG. 24H is a section view taken along line 24H-24H in FIG. 24F.

FIG. 25 is a perspective view of a surgical system in accordance with apreferred embodiment of a present invention.

FIG. 26 is a section view taken along line 26-26 in FIG. 25.

FIG. 27 is an end view of a probe in accordance with one embodiment of apresent invention.

FIG. 27A is an end view of a probe in accordance with one embodiment ofa present invention.

FIG. 28 is a section view taken along line 28-28 in FIG. 27.

FIG. 29 is a perspective view of a surgical system in accordance with apreferred embodiment of a present invention.

FIG. 30 is a section view taken along line 30-30 in FIG. 29.

FIG. 31 is an end view of a probe in accordance with one embodiment of apresent invention.

FIG. 31A is an end view of a probe in accordance with one embodiment ofa present invention.

FIG. 32 is a section view taken along line 32-32 in FIG. 31.

FIG. 33 is a perspective view of a surgical system in accordance with apreferred embodiment of a present invention.

FIG. 34 is a top view of a self-anchoring device in accordance with apreferred embodiment of a present invention.

FIG. 35 is a section view taken along line 35-35 in FIG. 34.

FIG. 36 is an enlarged section view taken along line 35-35 in FIG. 34.

FIG. 37 is a side view of a self-anchoring device in accordance with apreferred embodiment of a present invention.

FIG. 38 is a top view of the device illustrated in FIG. 37.

FIG. 39 is a side view of a self-anchoring device in accordance with apreferred embodiment of a present invention.

FIG. 40 is a top view of the device illustrated in FIG. 39.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following is a detailed description of the best presently knownmodes of carrying out the inventions. This description is not to betaken in a limiting sense, but is made merely for the purpose ofillustrating the general principles of the inventions.

The detailed description of the preferred embodiments is organized asfollows:

I. Introduction

II. Surgical Probes

III. Suction Devices For Use With Surgical Probes

IV. Clamp Based Devices

V. Coagulation Electrodes, Temperature Sensing And Power Control

VI. Stimulation Electrodes And Lesion Confirmation

VII. Tissue Stimulation And Sensing Probes

VIII. Self-Anchoring Tissue Stimulation and Sensing Devices

The section titles and overall organization of the present detaileddescription are for the purpose of convenience only and are not intendedto limit the present inventions.

I. Introduction

Surgical devices in accordance with the present inventions include oneor more tissue coagulation elements and/or one or more tissuestimulation elements. The tissue coagulation elements may be used to,for example, form therapeutic lesions and the tissue stimulationelements may be used to, for example, test whether or not the desiredtherapeutic lesion has been formed. The stimulation elements may also beused to stimulate tissue and sense electrical activity in tissue (suchas by pacing and recording) during a surgical procedure. The surgicaldevices may be used in conjunction with power supply and controlapparatus that supply and control power to the tissue coagulationelements in bipolar and/or unipolar modes. The surgical devices may alsobe used in conjunction with tissue stimulation apparatus, such as pacingand recording apparatus, which supply power that stimulates (but doesnot coagulate) tissue. Tissue stimulation may be used to confirm whetheror not a therapeutic lesion has been formed by, for example, supplyingtissue stimulation energy on one side of a lesion and/or monitoringtissue (either electrically or visually) on the other side of thelesion. Tissue stimulation may also be used to determine lesion depthand, correspondingly, whether or not a lesion is transmural.

II. Surgical Probes

As illustrated for example in FIG. 1, an exemplary surgical system 10 inaccordance with one embodiment of a present invention includes asurgical probe 100, a power supply and control apparatus 200, and atissue stimulation apparatus 300. The power supply and control apparatus200 and tissue stimulation apparatus 300 are discussed in Sections V andVI below. The surgical probe 100 includes a relatively short shaft 102with a proximal section 104, which is connected to a handle 106, and adistal section 108, on which coagulation electrodes 110 are supported.The coagulation electrodes 110 are discussed in Section V below. Thedistal section 108 also supports tissue stimulation electrodes 112 and114. The tissue stimulation electrodes 112 and 114, which are discussedin Section VI below, may also be used to sense local tissue activation.

Turning to FIGS. 2-5, the exemplary shaft proximal section 104 consistsof a hypotube 116, which is either rigid or relatively stiff, and anouter polymer tubing 118 over the hypotube. The handle 106 preferablyconsists of two molded handle halves and is provided with strain reliefelement 120. The shaft proximal section 104 in the illustratedembodiment may be from 4 inches to 18 inches in length and is preferably6 inches to 8 inches. The shaft distal section 108, which is preferablyeither malleable, somewhat flexible or some combination thereof, may befrom 1 inch to 10 inches in length and is preferably 3 to 5 inches.

As used herein the phrase “relatively stiff” means that the shaft (ordistal section or other structural element) is either rigid, malleable,or somewhat flexible. A rigid shaft cannot be bent. A malleable shaft isa shaft that can be readily bent by the physician to a desired shape,without springing back when released, so that it will remain in thatshape during the surgical procedure. Thus, the stiffness of a malleableshaft must be low enough to allow the shaft to be bent, but high enoughto resist bending when the forces associated with a surgical procedureare applied to the shaft. A somewhat flexible shaft will bend and springback when released. However, the force required to bend the shaft mustbe substantial. Rigid and somewhat flexible shafts are preferably formedfrom stainless steel, while malleable shafts are formed from annealedstainless steel. Additional information concerning “relatively stiff”shafts is provided in U.S. Pat. No. 6,142,994, which is incorporatedherein by reference.

In those instances where a malleable shaft proximal portion 104 isdesired, the hypotube 116 may be a heat treated malleable hypotube. Byselectively heat treating certain portions of the hypotube, one sectionof the hypotube can be made more malleable than the other. The outertubing 118 may be formed from Pebax® material, polyurethane, or othersuitable materials.

As noted above, the shaft distal section 108 can be either somewhatflexible, in that it will conform to a surface against which it ispressed and then spring back to its original shape when removed from thesurface, malleable, or some combination thereof. In the exemplaryimplementation illustrated in FIGS. 1-7, the distal section 108 includesa malleable proximal portion and a flexible distal portion. Although therelative lengths of the portions may vary to suit particularapplications, the malleable proximal portion and a flexible distalportion are equal in length in the illustrated embodiment.

Referring more specifically to FIGS. 4 and 5, the exemplary shaft distalsection 108 includes an outer member 122 that carries the electrodes110-114. The outer member 122 is a flexible tubular structure which hasan outer diameter that is, depending on the diameter of the electrodes110 and 112, typically between about 2 mm and about 4 mm. The outermember 122 in the illustrated embodiment, which is intended for use incardiovascular applications, typically has an outer diameter of about 3mm. Suitable support structure materials include, for example, flexiblebiocompatible thermoplastic tubing such as unbraided Pebax® material,polyethylene, or polyurethane tubing.

Turning to the interior of the shaft distal section 108, the exemplarymalleable portion includes a mandrel 124 (FIG. 4) made of a suitablymalleable material, such as annealed stainless steel or berylliumcopper, that may be fixed directly within the distal end of the shaft'shypotube 116 and secured by, for example, soldering, spot welding oradhesives. Sufficient space should be provided to allow passage of thepower lines 126, which are connected to the coagulation electrodes 110,the temperature sensor signal lines 128, which are connected totemperature sensors 130 (FIG. 5) such as thermocouples or thermistors,and signal lines 132, which are connected to the tissue stimulationelectrodes 112 and 114. As described in greater detail below, the powerlines 126 may be used to transmit energy from the power supply andcontrol apparatus 200 to the coagulation electrodes 110, while signallines 128 return temperature information from the temperature sensors130 to the power supply and control apparatus. The signal lines 132 maybe used to transmit tissue stimulation energy from the tissuestimulation apparatus 300 to the stimulation electrodes 112 and 114. Thesignal lines 132 may also be used to transmit the signals associatedwith local electrical activity when the tissue stimulation electrode 112and 114 are used for sensing. An insulating sleeve 134 is placed overthe mandrel 124 to protect the power lines 126, temperature sensorsignal lines 128 and signal lines 132. The insulating sleeve 134 ispreferably formed from Pebax® material, polyurethane, or other suitablematerials.

With respect to the flexible portion, a spring member 136, which ispreferably either a solid flat wire spring (FIG. 5), a round wire, or athree leaf flat wire Nitinol® spring, is connected to the distal end ofthe mandrel 124 with a crimp tube or other suitable instrumentality. Thedistal end of the spring member 136 is connected to the electrode 114by, for example, an adhesive that will also electrically insulate thespring member from the electrode. The electrode 114 is also secured tothe distal end of the outer member 122. Other spring members, formedfrom materials such as 17-7 or carpenter's steel, may also be used. Thespring member 136 is also enclosed within the insulating sleeve 134. Thespring member 136 may be pre-stressed so that the distal tip is pre-bentinto a desired shape. Additional details concerning distal sections thathave a malleable proximal portion and a flexible distal portion areprovided in U.S. Pat. No. 6,464,700, which is incorporated herein byreference.

In an alternative configuration, the distal section 108 may be formed bya hypotube that is simply a continuation of the shaft hypotube 116covered by a continuation of the outer tubing 118. However, the distalend hypotube can also be a separate element connected to the shafthypotube 116, if it is desired that the distal end hypotube havedifferent stiffness (or bending) properties than the shaft hypotube. Itshould also be noted that the distal section 108 may be made malleablefrom end to end by eliminating the spring member 136 and extending themalleable mandrel 124 to the electrode 114. Conversely, the distalsection 108 may be made flexible from end to end by eliminating themalleable mandrel 124 and extending the spring member 136 from thehypotube 116 to the electrode 114.

Turning to FIGS. 5 and 6, the power lines 126 and signal lines 128extend from the coagulation electrodes 110 and temperature sensors 130to a connector (such as the exemplary PC board 138) that is carried bythe handle 106. The handle 106 also includes a port 140 that isconfigured to receive a connector, such as the connector 206 (FIG. 1)from the power supply and control apparatus 200, for connection to thePC board 138. Openings 142 and 144 are provided for the signal lines132.

The exemplary surgical system 11, which is illustrated in FIGS. 6A and6B, includes a surgical probe 101, a power supply and control apparatus200, a tissue stimulation apparatus 300 and an EP recording apparatus301. The power supply and control apparatus 200 is discussed in SectionV, while the tissue stimulation apparatus 300 and EP recording apparatus301 are discussed in Section VI. The exemplary surgical probe 101 isessentially identical to the surgical probe 100 and similar elements arerepresented by similar reference numerals. Here, however, a plurality ofstimulation electrodes 112 are located along the length of the shaftdistal portion 108. In the illustrated embodiment, a stimulationelectrode 112 is located between each of the coagulation electrodes 110.There is also a stimulation electrode 112 proximal of the proximal-mostcoagulation electrode 110 and a stimulation electrode 112 distal of thedistal-most coagulation electrode 110. A stimulation electrode 114 isalso provided on the distal end of the probe. Signal lines 132, whichare connected to the tissue stimulation electrodes 112 and 114, extendthough a cable 115 and are connected to the EP recording apparatus 301with a connector 117.

In another alternative implementation, pairs of stimulation electrodes112 may be located between each of the coagulation electrodes 110,proximal of the proximal-most coagulation electrode, and distal of thedistal-most coagulation electrode. A stimulation electrode 114 on thedistal end of the probe may also be provided.

III. Suction Devices for Use with Surgical Probes

As illustrated for example in FIG. 7, an exemplary surgical system 20 inaccordance with one embodiment of a present invention includes asurgical probe 100′, a power supply and control apparatus 200, a tissuestimulation apparatus 300 and an EP recording apparatus 301. The powersupply and control apparatus 200 is discussed in Section V, while thetissue stimulation apparatus 300 and EP recording apparatus 301 arediscussed in Section VI. The exemplary system is also provided with asuction apparatus 400 that includes a suction source 402 and a suctiondevice 404 that may be removably secured to the distal section 108 ofthe surgical probe 100′. The suction device 404 is connected to thesuction source 402 by a flexible tube 406. When the suction source 402is actuated, the suction device 404 will fix the position of the distalsection of the surgical probe 100′ relative to the target tissue.Additionally, depending on the rigidity of the suction device 404 andthe rigidity of the tissue, the applied vacuum may also cause the tissueand electrodes 110 on the distal section 108 to come into contact withone another because portions of the suction device will deflect,portions of the tissue surface will deflect, or portions of both thesuction device and the tissue surface will deflect.

The surgical probe 100′ is substantially identical to surgical probe 100and similar elements are represented by similar reference numerals.Surgical probe 100′ does not, however, include the tissue stimulationelectrodes 112 and 114. Instead, as illustrated in FIG. 10, the suctiondevice 404 is provided with tissue stimulation electrodes 426 and, insome instances, sensing electrodes 428. The tissue stimulation andsensing electrodes 426 and 428, which are held firmly against tissuewhen the suction source 402 is activated, are discussed in Section VIbelow.

The exemplary suction source 402 may be any suitable device that iscapable of supplying the desired partial vacuum, which will typicallyrange from about 200 mmHg to about 700 mmHg. Turning to FIGS. 8-13, theexemplary suction device 404 includes a main body 407, a pair ofinternal suction lines 408 and a plurality of individual suction ports410. The suction tube 406 may be connected to the internal suction lines408 by a connector 412 such as, for example, the illustrated Luerconnector. The suction ports 410 are respectively connected to theinternal suction lines 408 by a plurality of apertures 414. The suctionports 410 are also formed in the curved bottom surface 416 (or “bottomwall”) of the main body 407 and define respective suction regions 418(FIG. 12). During use, the curved bottom surface will form a seal withthe tissue surface and air within the suction regions 418 will be drawnthrough the apertures 414, thereby causing the suction device 404 toadhere to the tissue surface.

The suction device 404 also includes a connector that enables it to beremovably secured to the distal portion 108 of the surgical probe 100′.Although the present inventions are not limited to any particularconnector, the connector in the exemplary embodiment is a slot 420 intowhich the surgical probe distal portion 108 may be inserted. The slot420 is generally semi-circular in cross-section and extends betweenabout 180 to 360 degrees, and preferably about 300 degrees. The diameterof the slot 420 will preferably be about the same as the diameter of thesurgical probe distal portion 108. As such, the distal portion 108 maybe removably snap fit into the slot 420. Additionally, once the surgicalprobe distal portion 108 is within the slot 420, it may be advanceddistally toward the suction device nose 422 and into an aperture 424 foranchoring (FIGS. 14 and 15).

The specific size and shape of the suction device 404 will, of course,depend on the intended application, as will the choice of materials.Although the present inventions are not limited to any particular sizes,shapes or materials, one exemplary implementation that is especiallywell suited for cardiac treatment and use with the above-describedsurgical probe 100′ is described hereafter. The suction device 404 isformed, preferably by molding, from a soft, flexible biocompatiblematerial such as silicone rubber or urethane that is capable ofwithstanding temperatures up to 120° C. without melting or burning. Whenmolded, the suction device 404 will be an integrally formed (i.e. onepiece) structure, although some or all of the connector 412 may be addedafter molding depending on the type of connector employed. The overalllength of the suction device 404, not including the connector 412, willbe slightly longer than the shaft distal portion 108, e.g. about 10 cmin an exemplary implementation where the distal portion is about 9 cm.

The exemplary suction ports 410 are generally concave and elliptical inshape and have a major diameter of about 5 mm, a minor diameter of about3 mm, a depth of about 2 mm. In the illustrated embodiment, the spacingcorresponds to the spacing of the electrodes on the associated probe.Alternatively, the exemplary elliptical (i.e. 5 mm×3 mm×2 mm) suctionports may be spaced apart by about 6 mm center-to-center. The distancebetween the bottom of the slot 420 and the bottom of the main body 407is about 5 mm. This exemplary configuration will result in the surgicalprobe 100′ and suction device 404 mating with one another in the mannerillustrated in FIGS. 14 and 15.

With respect to the electrical connection of the stimulation electrodes426 to the tissue stimulation apparatus 300 and EP recording apparatus301, and referring to FIGS. 12 and 13, the stimulation electrodes in theexemplary implementation are connected to signal lines 430 that extendfrom the stimulation electrodes, around the main body 407, to a signalline bundle 432 on the top of the main body. Similarly, signal lines 434extend from the sensing electrodes 428 to a signal line bundle 436. Asilicone rubber overmold 438 may be used to cover the individual signallines and signal line bundles in those instances where the main body 407is formed from silicone rubber. Alternatively, in those instances wherethe main body is formed from polyurethane, the signal lines and signalline bundles may be held in place with an elastic polyurethane adhesive.The signal lines in the bundles 432 and 436 pass through a cable 440(FIG. 7) and are connected to the EP recording apparatus 301 by aconnector 442. As discussed below, the EP recording apparatus 301 isconnected to, and directs the tissue stimulation and recordingassociated with, the tissue stimulation apparatus 300.

It should also be noted that, instead of the exemplary surgical probe100′, the exemplary suction device 404 may be secured to the distalportion of a conventional electrophysiology catheter. The distal portionof the catheter and suction device 404 could then be used to directlyplace electrodes against tissue during a surgical procedure. Theexemplary suction device 404 may also be permanently secured to asurgical probe or catheter by overmolding the suction device onto thesurgical probe or catheter.

IV. Clamp Based Devices

As illustrated for example in FIG. 16, an exemplary surgical system 30in accordance with one embodiment of a present invention includes anelectrophysiology clamp apparatus 500, a power supply and controlapparatus 200, and a tissue stimulation apparatus 300. The power supplyand control apparatus 200 and tissue stimulation apparatus 300 arediscussed in Sections V and VI below. The electrophysiology clampapparatus 500 includes a clamp and a tissue coagulation and stimulationassembly that may be secured to the clamp. As used herein, the term“clamp” includes, but is not limited to, clamps, clips, forceps,hemostats, and any other surgical device that includes a pair ofopposable clamp members that hold tissue, at least one of which ismovable relative to the other. In some instances, the clamp members areconnected to a scissors-like arrangement including a pair of handlesupporting arms that are pivotably connected to one another. The clampmembers are secured to one end of the arms and the handles are securedto the other end. Certain clamps that are particularly useful inminimally invasive procedures also include a pair of handles and a pairof clamp members. Here, however, the clamp members and handles are notmounted on the opposite ends of the same arm. Instead, the handles arecarried by one end of an elongate housing and the clamp members arecarried by the other. A suitable mechanical linkage located within thehousing causes the clamp members to move relative to one another inresponse to movement of the handles. The clamp members may be linear orhave a predefined curvature that is optimized for a particular surgicalprocedure or portion thereof. The clamp members may also be rigid ormalleable.

One example of a clamp is generally represented by reference numeral 502in FIGS. 16 and 22-24. Referring more specifically to FIGS. 22-24, theclamp 502 includes a pair of rigid arms 504 and 506 that are pivotablyconnected to one another by a pin 508. The proximal ends of the arms 504and 506 are respectively connected to a pair handle members 510 and 512,while the distal ends are respectively connected to a pair of clampmembers 514 and 516. The clamp members 514 and 516 may be rigid ormalleable and, if rigid, may be linear or have a pre-shaped curvature. Alocking device 518 locks the clamp in the closed orientation, andprevents the clamp members 514 and 516 from coming any closer to oneanother than is illustrated in FIG. 22, thereby defining a predeterminedspacing between the clamp members. The clamp 502 is also configured foruse with a pair of soft, deformable inserts (not shown) that may beremovably carried by the clamp members 514 and 516 and allow the clampto firmly grip a bodily structure without damaging the structure. Tothat end, the clamp members 514 and 516, each include a slot 520 (FIGS.23 and 24) that is provided with a sloped inlet area 522 and the insertsinclude mating structures that are removably friction fit within theslots. The present tissue coagulation and stimulation assemblies may bemounted on the clamp members in place of the inserts.

One example of a tissue coagulation and stimulation assembly, which isgenerally represented by reference numeral 524 in FIGS. 16-19, includesfirst and second tissue coagulation electrodes 526 a and 526 b, whichare discussed in Section V below, and first and second tissuestimulation electrodes 528 a and 528 b, which are discussed in SectionVI below. Typically, there will be about 1 to 3 mm between the distalends of the coagulation electrodes 526 a and 526 b and the stimulationelectrodes 528 a and 528 b. The electrodes are carried on supportstructures 530 a and 530 b, which are connected to a flexible cable 532by a molded plastic junction 534. The first and second coagulationelectrodes 526 a and 526 b are also relatively long electrodes (e.g.about 3 to 8 cm) and, to that end, power lines 536 are connected to eachlongitudinal end of the first tissue coagulation electrode 526 a andreturn lines 538 are connected to each longitudinal end of the secondtissue coagulation electrode 526 b. It should be noted that although thereturn lines 538 may be used to return power when the surgical system 30is operating in a bipolar mode, the return lines may also be used tosupply power when the system is operating in a unipolar mode.

The tissue stimulation electrode 528 a is connected to a signal line540, and the tissue stimulation electrode 528 b is connected to a signalline 542. The signal lines 540 and 542 may be used for transmission andreturn, respectively, when the system is being operated in a bipolarmode, and both may be used for transmission when the system is beingoperated in unipolar mode. The first and second tissue stimulationelectrodes 528 a and 528 b, as well as the signal lines 540 and 542, mayalso be used to transmit signals when the stimulation electrodes areused for sensing and recording purposes.

In the exemplary embodiment, a plurality of temperature sensors 130(FIG. 21), such as thermocouples or thermistors are carried on thesupport structures 530 a and 530 b. There are four (4) temperaturesensors 130 associated with each tissue coagulation electrode 526 a and526 b in the exemplary embodiment. Signal lines 544 are connected toeach of the temperature sensors 130.

In an alternative arrangement, one or both of the first and tissuesecond coagulation electrodes 526 a and 526 b may be split into twoelectrodes that are about 1.5 cm to 4 cm in length and separated byabout 1 to 3 mm. Here, each electrode will be connected to a singlepower or return line and two temperature sensors 130 will be associatedwith each electrode.

As described in greater detail below, the power supply lines 536 may beused to transmit energy from the power supply and control apparatus 200to the coagulation electrode 526 a (which is returned by way ofcoagulation electrode 526 b and return lines 538), while the signallines 544 return temperature information from the temperature sensors130 to the power supply and control apparatus. The signal line 540 maybe used to transmit tissue stimulation energy from the tissuestimulation apparatus 300 to the stimulation electrode 528 a. Thestimulation energy is returned to the tissue stimulation apparatus 300by way of the stimulation electrode 528 b and signal line 542. The powersupply and return lines 536 and 538 and signal lines 540-544 extend fromthe electrodes 526 a-528 b and temperature sensors 130, through thecable 532, to a handle 545. The power supply and return lines 536 and538 and signal lines 544 are connected to a PC board 546 that is carriedby the handle 545. The handle 545 also includes a port (not shown) for aconnector 206′ from the power supply and control apparatus 200 whichconnects to the PC board 546, and openings (not shown) for signal lines540 and 542, which are connected to the tissue stimulation apparatus300.

The exemplary tissue coagulation and stimulation assembly 524 alsoincludes a pair of base members 548 a and 548 b which are used toconnect the assembly to the clamp 502. Although the configuration of theenergy transmission and stimulation assembly may vary from applicationto application to suit particular situations, the exemplary energytransmission and stimulation assembly 524 is configured such that theelectrodes 526 a and 526 b will be parallel to one another as well asrelatively close to one another (i.e. a spacing of about 1-10 mm) whenthe clamp 502 is in the closed orientation. The stimulation electrodes528 a and 528 b will typically be about 5 mm to 50 mm apart when theclamp 502 is opened (in full or in part). Such an arrangement will allowthe energy transmission and stimulation assembly to grip a bodilystructure without cutting through the structure. Referring morespecifically to FIGS. 20-24, the base member 548 a includes a mainportion 550, with a groove 552 that is configured to receive the supportstructure 530 a and electrode 526 a, and a connector 554 that isconfigured to removably mate with the slot 520 in the clamp 502. [Itshould be noted that the configuration of the base member 548 b isidentical to that of the base member 548 a in the illustratedembodiment.] About 20% of the electrode surface (i.e. about 75° of the360° circumference) is exposed in the illustrated embodiment. Adhesivemay be used to hold the electrode 526 a and support structure 530 a inplace. The exemplary connector 554 is provided with a relatively thinportion 556 and a relatively wide portion 558, which may consist of aplurality of spaced members (as shown) or an elongate unitary structure,in order to correspond to the shape of the slot 520.

The base members 548 a and 548 b are preferably formed frompolyurethane. The length of the base members in the exemplary energytransmission assemblies will vary according to the intended application.In the area of cardiovascular treatments, it is anticipated thatsuitable lengths will range from, but are not limited to, about 4 cm toabout 10 cm. In the exemplary implementation, where the electrodes 526 aand 526 b are preferably about 6.4 cm, the base members 548 a and 548 bwill be about 6.6 cm.

The exemplary clamp apparatus 500 is not limited to the exemplaryimplementation described above and is susceptible to a wide variety ofmodifications. By way of example, and referring to FIGS. 24A and 24B,the tissue coagulation and stimulation assembly may be modified suchthat the position of the first and second tissue stimulation electrodes528 a and 528 b relative to the first and tissue second coagulationelectrodes 526 a and 526 b and/or the distal ends of the base membersmay be varied, as they are in base members 548 a′ and 548 a″.

Other exemplary clamp apparatus include a tissue coagulation andstimulation assembly wherein a plurality of stimulation electrodes areassociated with one (or both) of coagulation electrodes. The stimulationelectrodes may, for example, be located on opposite sides of acoagulation electrode so that the stimulation electrodes will be onopposite side of the lesion for stimulation and sensing purposes. Onesuch tissue coagulation and stimulation assembly is generallyrepresented by reference numeral 524′ and is illustrated in FIGS. 24C-H.The tissue coagulation and stimulation assembly 524′ is substantiallysimilar to the tissue coagulation and stimulation assembly 524illustrated in FIGS. 17-21 and similar elements are represented bysimilar reference numerals. Here, however, pairs of stimulationelectrodes 529 a 1/529 a 2 and 529 b 1/529 b 2 are positioned onopposite sides of the coagulation electrode 526 a. The spacing betweenthe stimulation electrodes 529 a 1/529 a 2 and 529 b 1/529 b 2, whichare discussed in Section VI below, and the coagulation electrode 526 awill typically be about 1 mm. The coagulation electrodes 526 a and 526 bare carried on support structures 530 a and 530 b. The stimulationelectrodes 529 a 1/529 a 2 and 529 b 1/529 b 2 are carried on supportstructures 531 a and 531 b.

The exemplary tissue coagulation and stimulation assembly 524′ alsoincludes a pair of base members 549 a and 549 b which are used toconnect the assembly to the clamp 502 in the manner described above withreference to base members 548 a and 548 b. Referring more specificallyto FIGS. 24F-24G, the base member 549 a includes a main portion 551,with a groove 552 that is configured to receive the support structure530 a and electrode 526 a, and a pair of grooves 553 that are configuredto receive the stimulation electrodes 529 a 1/529 a 2 and 529 b 1/529 b2 and support structures 531 a and 531 b. A connector 554 is configuredto removably mate with the slot 520 in the clamp 502. The configurationof the base member 549 b is identical to that of the base member 548 bin the illustrated embodiment. Alternatively, the base member 549 b maybe configured to carry stimulation electrodes in the same manner as basemember 549 a. Still another alternative is to configure the assemblysuch that stimulation electrodes 529 a 1/529 a 2 are carried base member549 a, stimulation electrodes 529 b 1/529 b 2 are carried base member549 b, and stimulation electrodes 529 a 1/529 a 2 and stimulationelectrodes 529 b 1/529 b 2 are on opposite side of the coagulationelectrodes.

The tissue stimulation electrodes 529 a 1/529 a 2 are connected torespective signal lines 540 and 542, as are the tissue stimulationelectrodes 529 b 1/529 b 2. The signal lines 540 and 542 may be used fortransmission and/or return depending upon the manner in which theelectrodes are being used. For example, the stimulation electrodes 529 a1/529 a 2 may be used in bipolar mode to transmit stimulation energy andthe stimulation electrodes 529 b 1/529 b 2 may be used in bipolar modeto sense local activation.

Finally, the clamp and the tissue coagulation and stimulation assembliesdescribed above may be combined into an integral unit that cannot bereadily separated. For example, the base members may be molded onto theclamp members. Such base members would, for example, extend completelyaround the each clamp member and/or include portions that are moldedinto the slots.

V. Coagulation Electrodes, Temperature Sensing and Power Control

In each of the surgical systems illustrated in FIGS. 1-24H, coagulationelectrodes adapted to transmit RF energy are employed. However, othertypes of coagulation elements, such as such as lumens for chemicalablation, laser arrays, ultrasonic transducers, microwave electrodes,ohmically heated hot wires, and the like may be substituted for thecoagulation electrodes. Coagulation electrodes may be arranged as aseries of spaced electrodes or, alternatively, a single elongatecoagulation electrode may be employed.

Although the present inventions are not limited to any particularnumber, the exemplary surgical probes 100, 100′ and 101 illustrated inFIGS. 1-15 each include seven spaced coagulation electrodes 110, whilethe various clamp apparatus 500 illustrated in FIGS. 16-24H includes asingle electrode 526 a/526 b carried on each of the clamp members 514and 516. The coagulation electrodes are preferably in the form of wound,spiral closed coils. The coils are made of electrically conductingmaterial, like copper alloy, platinum, or stainless steel, orcompositions such as drawn-filled tubing (e.g. a copper core with aplatinum jacket). The electrically conducting material of the coils canbe further coated with platinum-iridium or gold to improve itsconduction properties and biocompatibility. Preferred coil coagulationelectrodes are disclosed in U.S. Pat. Nos. 5,797,905 and 6,245,068.

Alternatively, the coagulation electrodes 110 may be in the form ofsolid rings of conductive material, like platinum, or can comprise aconductive material, like platinum-iridium or gold, coated upon thedevice using conventional coating techniques or an ion beam assisteddeposition (IBAD) process. For better adherence, an undercoating ofnickel, silver or titanium can be applied. The coagulation electrodescan also be in the form of helical ribbons. The electrodes can also beformed with a conductive ink compound that is pad printed onto anon-conductive tubular body. A preferred conductive ink compound is asilver-based flexible adhesive conductive ink (polyurethane binder),however other metal-based adhesive conductive inks such asplatinum-based, gold-based, copper-based, etc., may also be used to formelectrodes. Such inks are more flexible than epoxy-based inks. Open coilelectrodes may also be employed for coagulation.

The exemplary flexible coagulation electrodes 110 carried by thesurgical probes 100, 100′ and 101 illustrated in FIGS. 1-15 arepreferably about 4 mm to about 20 mm in length. In the preferredembodiments, the electrodes are 12.5 mm in length with 1 mm to 3 mmspacing, which will result the creation of continuous lesion patterns intissue when coagulation energy is applied simultaneously from adjacentelectrodes through tissue to an indifferent electrode. For rigidcoagulation electrodes, the length of the each electrode can vary fromabout 2 mm to about 10 mm. Using multiple rigid electrodes longer thanabout 10 mm each adversely effects the overall flexibility of thedevice, while electrodes having lengths of less than about 2 mm do notconsistently form the desired continuous lesion patterns. The diameter,whether flexible or rigid, will typically be about 3 mm. Turning to therelatively long coagulation electrodes 526 a and 526 b carried by theclamp 502 illustrated in FIGS. 16-24H, for cardiovascular applications,the length is preferably between about 2 cm and 8 cm in those instanceswhere power is supplied at both longitudinal ends of each electrode, andthe end to end resistance is about 5 ohm to about 15 ohm. The diameterof the electrodes described above preferably ranges from about 1.5 mm toabout 3 mm for cardiovascular applications and, in one preferredimplementation, the outer diameter is about 2 mm.

In the exemplary embodiments, the temperature sensors 130 are preferablylocated within a linear channel, such as the channel 131 in FIG. 5,which is formed in the shaft distal portion 108 (FIGS. 1-15) or in thechannel 131 in FIG. 21, which is formed in the support structures 530 aand 530 b (FIGS. 16-21 and 24C-24H). The linear channel insures that thetemperature sensors will all face in the same direction (e.g. facingtissue) and be arranged in linear fashion. This arrangement results inmore accurate temperature readings which, in turn, results in bettertemperature control. As such, the actual tissue temperature will moreaccurately correspond to the temperature set by the physician on thepower supply and control device, thereby providing the physician withbetter control of the lesion creation process and reducing thelikelihood that embolic materials will be formed. A referencethermocouple may also be provided.

The power supply and control system 200 includes an electrosurgical unit(“ESU”) 202 that supplies and controls RF power. A suitable ESU is theModel 4810 ESU sold by Boston Scientific Corporation of Natick, Mass.,which is capable of supplying and controlling power on anelectrode-by-electrode basis. This is sometimes referred to as“multi-channel control.” The ESU 202 transmits energy to the coagulationelectrodes and receives signal from the temperature sensors by way of acable 204 and a connector 206, which may be connected to the PC board onthe surgical probe or clamp in the manner described above. The amount ofpower required to coagulate tissue ranges from 5 to 150 W. The exemplaryESU 202 is operable in a bipolar mode, where tissue coagulation energyemitted by one of the coagulation electrodes is returned through one ofthe other coagulation electrodes, and a unipolar mode, where the tissuecoagulation energy emitted by the coagulation electrodes is returnedthrough one or more indifferent electrodes 208 that are externallyattached to the skin of the patient with a patch, or one or moreelectrodes (not shown) that are positioned in the blood pool, and acable 210. Information concerning suitable temperature sensing and RFpower supply and control is disclosed in U.S. Pat. Nos. 5,456,682,5,582,609 and 5,755,715. Another alternative is to supply power in thecombined bipolar/unipolar mode described in U.S. application Ser. No.10/368,108, which is entitled “Power Supply And Control Apparatus AndElectrophysiology Systems For Use With Same” and incorporated herein byreference.

With respect to the surgical systems 10, 11 and 20 illustrated in FIGS.1-15, a single power line 126 is connected to each coagulation electrode110. Typically, there are two temperature sensors 130 for eachcoagulation electrode 110. The ESU 202 individually powers and controlseach coagulation electrode 110 based on the hottest of the two measuredtemperatures at that particular electrode.

In the surgical system 30 illustrated in FIGS. 16-24H, first and secondpower lines 536 are respectively connected to the longitudinal ends ofthe coagulation electrode 526 a, first and second return lines 538 arerespectively connected to the longitudinal ends of the coagulationelectrode 526 b, and two pairs of temperature sensors 130 (i.e. fourtemperature sensors) are provided for each of the coagulationelectrodes. Each temperature sensor pair includes one temperature sensor130 at a longitudinal end of the associated coagulation electrode andone temperature sensor located a distance equal to about ⅓ of the totalelectrode length from the longitudinal end. The ESU 202 will typicallybe operated in bipolar mode and energy supplied to the coagulationelectrode 526 a will be returned to the ESU by way of the coagulationelectrode 526 b. As such, the ESU connector 206′ is connected to thepower supply and return lines 536 and 538.

The ESU 202 in the exemplary surgical system 30 may be used toindividually power and control two portions of the coagulation electrode526 a (one portion on either side of the longitudinal mid-point of theelectrode) during a lesion formation procedure. Power to each portion,which has one power line 536 connected thereto and two temperaturesensors 130 associated therewith, is controlled based on the highest ofthe two temperatures sensed by the two temperature sensors associatedwith that portion. Additional details concerning this power supply andcontrol technique are provided in U.S. application Ser. No. 10/255,025,which is entitled “Electrophysiology Electrode Having Multiple PowerConnections And Electrophysiology Devices Including The Same” andincorporated herein by reference.

The exemplary ESU 202 is also provided with power output and returnconnectors 212 and 214 (FIGS. 1, 6A, 7 and 16), for connection tocorresponding connectors on the power output and return cables 204 and210, that have different configurations in order to prevent improperconnections.

VI. Stimulation Electrodes and Lesion Confirmation

In addition to forming lesions, the exemplary surgical systemsillustrated in FIGS. 1-24H may also be used to determine whether or nottherapeutic lesions have been properly formed by, for example, supplyingtissue stimulation energy on one side of a lesion. The tissue on theother side of the lesion may then be monitored to determine whether anexcitation block (typically the result of a continuous transmurallesion) has been formed in the target tissue. Tissue stimulation energymay also be used to determine lesion depth, which in turn, allows thephysician to determine whether or not a lesion is transmural. In theexemplary implementations, the tissue stimulation energy is provided bya tissue stimulation apparatus 300 that is capable of providing a pulseof energy that stimulates (but does not coagulate) tissue. One exemplarytissue stimulation apparatus 300 is a conventional pacing apparatus,such as the Medtronic Model Nos. 5330 and 5388 external pulsegenerators. An ECG machine that is capable of monitoring and recordingelectrical impulses sensed by electrodes may also be provided.

With respect to the stimulation energy, the power delivered to tissuefor stimulation purposes will typically be significantly less than thatwhich would form a transmural or otherwise therapeutic lesion in tissue.With respect to the larger stimulation electrodes 112, 114, 528 a, 528b, 529 a 1, 529 a 2, 529 b 1 and 529 a 2 discussed with respect to FIGS.1-6B, 16-21 and 24A-24H, which may also be used for sensing, anexemplary stimulation energy delivery would consist of two stimulationpulses per second, each pulse being 1 millisecond. The maximum amplitudewould be 20 mA, which would create 1 V, for a total power delivery of 40μW. Turning to the smaller stimulation and sensing electrodes 426, 428and 604, an exemplary stimulation energy delivery would consist of twostimulation pulses per second, each pulse being 1 millisecond. Themaximum amplitude would be 10 mA, which would create 0.5 V, for a totalpower delivery of 10 μW. As noted above, the amount of power required tocoagulate tissue ranges from 5 to 150 W.

In order to facilitate the connection to the tissue stimulationapparatus 300, the surgical devices discussed above with reference toFIGS. 1-6 and 16-32 are connectors 302 (both transmission and return)that are typically associated with pacing apparatus. Suitable connectorsinclude, for example, 2 mm Hirshman pins. The connectors 302 may beindividually connected to the tissue stimulation apparatus 300 (asshown) or combined into a single unit. The configuration of theconnectors 302 will also typically be different than the ESU connectors212 and 214 to prevent improper connections. In the embodimentillustrated in FIGS. 6A and 6B, on the other hand, there are far morestimulation electrodes and a single connector 117 is used to connect thestimulation electrodes to the EP recording apparatus 301. Similarly, inFIGS. 7-15, where there are many stimulation electrodes, as well as acorresponding number of sensing electrodes, a single connector 442 isused to connect the electrodes to the EP recording apparatus 301. Asuitable EP recording apparatus is the Prucka CardioLab 7000® from GEMedical Systems. Preferably, the configuration of the connectors 117 and442 will be different than the ESU connectors 212 and 214 to preventimproper connections.

It should also be noted that the functionality of the tissue stimulationapparatus 300 may be incorporated into the ESU 202. Here, however, ESUand associated surgical devices should be configured such thatcoagulation electrodes will only receive coagulation energy and thestimulation electrodes will only receive stimulation energy. Here too,this may be accomplished with different connector configurations. Thefunctionality of the tissue stimulation apparatus 300 and the EPrecording apparatus 301 may also be combined into a single device.

Generally speaking, the present surgical systems may be used to test theeffectiveness of a lesion as follows. After the lesion is formed, thephysician may use the same surgical device that was used to form thelesion (e.g. the surgical probe, surgical probe and suction device, orclamp based electrophysiology device) to perform a lesion evaluation. Asdiscussed in greater detail below, the stimulation electrodes that areprovided on surgical devices may be used to stimulate tissue on one sideof a lesion by pacing at a higher rate than normal (e.g. 120beats/minute). The local activation, if any, on the other side of thelesion will indicate whether or not the excitation block is incomplete.The stimulation electrodes may also be used to sense tissue within anisolated tissue region around which a lesion has been formed. Localactivation within the isolated region from the heart's naturalstimulation is indicative of a gap in the lesion. Additionally, thestimulation electrodes may be used to determine lesion depth.

There are a number of benefits associated with the present surgicalsystems. For example, the placement of tissue stimulation electrodes onthe same surgical device as the tissue coagulation electrodes allows thephysician to quickly and easily evaluate a lesion after it has beenformed.

Referring to the exemplary surgical system 10 illustrated in FIGS. 1-6,the surgical probe 100 is provided with a pair of tissue stimulationelectrodes 112 and 114 that may be connected to the tissue stimulationapparatus 300 and used to provide stimulation energy. The tissuestimulation electrodes 112 and 114 may also be used for sensing localtissue activation. Typically, the stimulation electrodes 112 and 114will operate in a bipolar mode, but may be operated in unipolar mode ifdesired. The stimulation electrodes 112 and 114 are typically relativelysmall (i.e. too small to form transmural myocardial lesions). In theexemplary embodiment, stimulation electrode 112 is a ring electrode thatis about 0.5 mm to 2 mm in length, the stimulation electrode 114 is atip electrode that is about 0.5 mm to 2 mm in length, and the spacingtherebetween is about 0.5 mm to 2 mm. Alternatively, the stimulationelectrode 114 may be in the form of a ring electrode. Stimulationelectrode 112 is about 1 mm to 3 mm from the distal-most coagulationelectrode 110. With respect to materials, the stimulation electrodes 112and 114 may be formed from the same materials as the coagulationelectrodes 110. The diameter of the electrodes 112 and 114 preferablyranges from about 1.5 mm to about 3 mm for cardiovascular applicationsand, in one preferred implementation, the outer diameter is about 2 mm.

The exemplary surgical system 10 may be used to test the quality oflesions formed during a lesion formation procedure in a variety of ways.In the context of pulmonary vein isolation, for example, the coagulationelectrodes 110 may be used to form continuous lesions around thepulmonary veins to isolated them from the left atria. Typically, a firstlesion will be formed around the right pulmonary vein pair and a secondlesion will be formed around the left pulmonary vein pair. Thestimulation electrodes 112 and 114 may then be used to providestimulation energy to the area within the first lesion. The tissue onthe other side of the lesion may be monitored (electrically or visually)to determine whether the excitation block formed by the first lesion iscomplete. A similar procedure may be performed with respect to thesecond lesion. Alternatively, the stimulation electrodes 112 and 114 maybe used to sense tissue within the area defined by the first lesion todetermine whether heart's natural stimulation will produce localactivation within the tissue area defined by the lesion. No localactivation within the area defined by the lesion is indicative of theformation of a complete excitation block, while local activation isindicative of a gap in the lesion. A similar procedure may be performedwith respect to the second lesion. It should also be noted that thesurgical system 10 may be used both epicardial and endocardialprocedures and that stimulation electrodes 112 and 114 may be usedindividually in unipolar versions of the aforementioned procedures ifdesired.

The tissue stimulation electrodes 112 and 114 in the exemplary surgicalprobe 101 illustrated in FIGS. 6A and 6B have the same configuration asthe tissue stimulation electrodes in the surgical probe 100 and thesurgical system 11 may be used to test the quality of lesions in themanner described above. Additionally, the surgical system 11 may be usedto determine lesion depth and, correspondingly, whether or not a lesionis transmural at various points along the length of the lesion.Stimulation energy may be used to determine lesion depth becausenon-viable tissue (e.g. coagulated tissue) cannot be stimulated and willnot propagate stimulation energy to nearby tissue. As such, when theapplication of stimulation energy that should stimulate tissue at aknown depth fails to do so, and that depth is greater than or equal tothe thickness of the body structure, it may be inferred that atransmural lesion has been formed.

In the context of lesions formed within the heart, for example,localized current densities must exceed about 2 mA/cm² to stimulateheart tissue. With respect to current transmitted from an electrode totissue, the current density is about l/2πr², where r is the distancefrom the electrode. Thus, a 1 mA stimulation pulse will typicallystimulate viable tissue that is no more than about 2.8 mm from theelectrode, a 2 mA stimulation pulse will typically stimulate viabletissue that is no more than about 4.0 mm from the electrode, a 10 mAstimulation pulse will typically stimulate viable tissue that is no morethan about 9.0 mm from the electrode, and a 20 mA stimulation pulse willtypically stimulate viable tissue that is no more than about 13.0 mmfrom the electrode. By varying the amplitude of the stimulation energypulses over a range of 1 to 20 mA, it is possible to determine how farviable tissue is from the electrode. For example, the left atrium isabout 3 mm thick and accordingly, failure to stimulate with a 2 mAstimulation pulse indicates that a transmural lesion has been formed inthe vicinity of the stimulation electrode.

Referring to the exemplary surgical probe 101, and as noted above, thetissue stimulation electrodes 112 are located between the coagulationelectrodes 110 and proximal of the proximal-most coagulation electrode,while the stimulation electrode 114 is distal of the distal-mostcoagulation electrode. This arrangement allows the physician to testvarious points along the length of a lesion when all of the coagulationelectrodes 110 are used to form the lesion (without moving the probe).Alternatively, if only the middle three coagulation electrodes 110 areused to form a lesion, for example, then the adjacent four tissuestimulation electrodes 112 could be used to stimulate tissue todetermine whether or not the lesion is transmural.

The exemplary surgical system 11 may be used to test the quality oflesions formed during a lesion formation procedure in a variety of ways.In the context of lesions within the left atrium, for example, thecoagulation electrodes 110 may be used to form a continuous lesion (e.g.around one or more pulmonary veins, or as part of a pattern oftherapeutic lesions). After the lesion has been formed, and withoutmoving the surgical probe 101, one or more of the stimulation electrodes112 and 114 may be used to provide stimulation energy to the coagulatedtissue. For example, the stimulation electrodes 112 and 114, which arelocated along the linear or curvilinear region of coagulated tissue maybe individually provided with pulses of stimulation energy. Themagnitude of the pulses, which should be chosen so as to correspond tothe thickness of the tissue structure, will be about 2 mA in the leftatrium example. Viable tissue within the left atrium may be monitored(electrically or visually) after each pulse to determine whether thelesion is transmural. More specifically, a lack of local activationwithin the left atrium from the pulse indicates that the lesion is deepenough (i.e. transmural) in the vicinity of the associated stimulationelectrode, while local activation indicates that the lesion is nottransmural in the region of the stimulation electrode. In thoseinstances where the lesion (or portion thereof) is not transmural,additional coagulation with the coagulation electrodes 110, typically ata higher power level than originally employed, may be performed. Itshould also be noted that the surgical system 11 may be used bothepicardial and endocardial procedures.

Turning to the exemplary surgical system 20 illustrated in FIGS. 7-15,and referring more specifically to FIG. 14, the suction device 404 isprovided with longitudinally extending bipolar pairs of tissuestimulation electrodes 426 and longitudinally extending bipolar pairs ofsensing electrodes 428 near the lateral edges of the suction device. Inthe illustrated embodiment, a plurality of bipolar pairs of stimulationelectrodes 426 extend along essentially the entire length of one side ofthe suction device 404, while a plurality of bipolar pairs of sensingelectrodes 428 extend along essentially the entire length of the otherside of the suction device. Each bipolar pair is adjacent to one of thesuction ports 410 and, accordingly, the electrodes will be held firmlyagainst tissue when suction force is applied. The stimulation electrodes426 are located on one side of the slot 420 and the sensing electrodes428 are located on the other. As such, the tissue stimulation andsensing electrodes 426 and 428 will be on opposite sides of the surgicalprobe distal section 108 and the coagulation electrodes 110, as well ason opposite sides of the lesion formed by the coagulation electrodes.

There are, of course, a wide variety of alternative stimulation andsensing electrode schemes. By way of example, but not limitation, thenumber of bipolar pairs of tissue stimulation and sensing electrodes 426and 428 may range from a large number of pairs (as shown) to a singlepair tissue stimulation electrodes and a single pair sensing electrodes.The single pairs may be located near the middle (measuredlongitudinally) of the suction device 404. Another alternative isunipolar stimulation and sensing. Here, single stimulation electrodes(as opposed to a bipolar pair) may be positioned adjacent to each of thesuction ports 410 on one side of the suction device 404 and singlesensing electrodes may be positioned adjacent to each of the suctionports on the other side of the suction device.

With respect to configuration and manufacture, the exemplary tissuestimulation and sensing electrodes 426 and 428 may be relatively small(i.e. too small to form transmural myocardial lesions), low profiledevices. Suitable sizes are about 0.5 mm to 1 mm in diameter, and asuitable thickness is about 0.01 mm. Such electrodes may be formed bycoating a conductive material onto the suction device 404 usingconventional coating techniques or an IBAD process. Suitable conductivematerials include platinum-iridium and gold. An undercoating of nickel,silver or titanium may be applied to improve adherence. Conductive inkcompounds, such as silver-based flexible adhesive conductive ink(polyurethane binder) or metal-based adhesive conductive inks (e.g.platinum, gold, or copper based) may also be pad printed onto thesuction device 404. The signal lines 430 and 434 are also very thin(e.g. about 40-50 gauge wires).

The exemplary surgical system 20 may be used to test the quality oflesions formed during a lesion formation procedure in a variety of ways.For example, the suction source 402 may be used to maintain the positionof the suction device 404 after power transmission from the coagulationelectrodes 110 on surgical probe 100′ has ended. A pulse of stimulationenergy (here, about 10 mA) may be applied to viable tissue on one sideof the lesion by a pair of stimulation electrodes (such as the pairidentified by reference numeral 426 a in FIG. 14). The viable tissue onthe other side of the lesion may be monitored with a pair of sensingelectrodes (such as the pair identified by reference numeral 428 a inFIG. 14) to detect the local excitation from the pulse of stimulationenergy. The tissue stimulation apparatus 300 will measure the amount oftime between the delivery of the pulse to the tissue by the stimulationelectrode pair 426 a and the detection of the local activation by thesensing electrode pair 428 a on the other side of the lesion. The amountof time that between pulse delivery on one side of the lesion and localactivation on the other (sometimes referred to as a “conduction delay”)is indicative of the quality of the lesion.

In the context of the formation of lesions within the heart, theconduction delay from the stimulation electrode pair 426 a and thesensing electrode pair 428 a will typically be about 10 ms when thedistance between the pairs is about 1 cm, absent a conduction block.Here, the excitation pulse will travel a relatively short distance.Conversely, when a complete conduction block is formed between thestimulation and sensing pairs, the excitation pulse will be forced totravel around the lesion. The longer travel distance results in a longerconduction delay, which is indicative of the formation of a therapeuticlesion. For example, a continuous 50 cm transmural lesion that creates acomplete conduction block along its length will typical increase theconduction delay to about 50 ms.

The exemplary EP recording apparatus 301 may be configured to simplydisplay measured conduction delays. Alternatively, the EP recordingapparatus 301 may be used to store expected propagation delays forvarious tissue types and suction device configurations (including thepositioning of the stimulation and sensing electrodes). The EP recordingapparatus 301 will compare the expected propagation delay (e.g. 10 ms)with no block to the measured propagation delay (e.g. 50 ms) anddetermine whether or not a complete conduction block has been formed.The EP recording apparatus 301 would then provide an audible or visualindication concerning the status of the lesion.

It should also be noted that, in a preferred testing method, the lesionwill be tested at various points along its length, one point at a time.The lesion may be tested with each of the stimulation and sensingelectrode pairs that are adjacent to a coagulation electrode that wasused to form a lesion. If for example, the proximal four coagulationelectrodes are used to form a lesion, then the proximal four pairs ofstimulation and sensing electrodes will be used (one stimulation/sensingat a time) to determine whether or not the lesion creating procedurecreated a complete conduction block.

Referring now to the exemplary surgical system 30 illustrated in FIGS.16-24B, and to FIG. 16 in particular, the energy transmission andstimulation assembly 524 includes first and second tissue stimulationelectrodes 528 a and 528 b. The stimulation electrodes 528 a and 528 bare preferably tip electrodes that are about 1 mm to 2 mm in length,about 2 mm to 4 mm in diameter, and carried on the distal ends of thesupport structures 530 a and 530 b. The stimulation electrodes 528 a and528 b are also about 1 mm to 3 mm from the distal ends of thecoagulation electrodes 526 a and 526 b. The stimulation electrodes may,alternatively, be ring electrodes that are carried near the distal endsof the support structures 530 a and 530 b. Another alternative is toplace both stimulation electrodes on one of the support structures in amanner similar to the surgical probe 100 illustrated in FIG. 1. Thestimulation electrodes 528 a and 528 b may also be formed from thematerials and methods described above with respect to stimulationelectrodes 112 and 114.

Turning to exemplary energy transmission and stimulation assembly 524′illustrated in FIGS. 24C-24H, the stimulation electrodes 529 a 1/529 a 2and 529 b 1/529 b 2 are typically relatively small ring electrodes (i.e.too small to form transmural myocardial lesions) that are about 0.5 mmto 2 mm in length and about 1.5 mm to 3 mm in diameter.

The exemplary surgical system 30 may be used to test the quality oflesions formed during a lesion formation procedure in a variety of ways.For example, in the context of the treatment of atrial fibrillation, thesurgical system 30 may be used to form lesions around one or morepulmonary veins to isolated the left atria from arrhythmias thatoriginate in the pulmonary veins. In one exemplary procedure, the clamp502 may be positioned around a pair of pulmonary veins and thecoagulation electrodes 526 a and 526 b used to form a lesion around thepair. The stimulation electrodes 528 a and 528 b may then be used tosupply a bipolar pacing pulse (e.g. about 20 mA) on the side of thelesion opposite the left atrium. The physician can determine whether ornot a therapeutic lesion (or “complete block”) has been formed byobserving the left atrium. If the pacing pulse is able to cross thelesion, the heart will beat faster (e.g. 120 beats/minute). This may bedetermined by observation or by use of an ECG machine that is monitoringthe heart. Here, additional coagulation will be required to complete thelesion. The failure to stimulate the heart from the side of the lesionopposite the left atrium is, on the other hand, indicative of theformation of a therapeutic lesion. Nevertheless, because muscle bundlesare not always connected near the pulmonary veins, it is preferable thatthe stimulation energy be applied to a number of tissue areas on theside of the lesion opposite the left atrium to reduce the possibility offalse negatives.

Alternatively, the stimulation electrodes 528 a and 528 b may then beused to monitor tissue within the region that was intended to beisolated. In the context of pulmonary vein isolation, for example, thestimulation electrodes 528 a and 528 b may be placed in contact withviable tissue on the pulmonary vein side of the lesion. Local activationwithin the isolated region from the heart's natural stimulation isindicative of a gap in the lesion.

The stimulation electrodes 528 a and 528 b may also be used in aunipolar operation similar to the bipolar operation discussed above withreference to stimulation and sensing electrodes pairs 426 a and 428 a.More specifically, the clamp members 514 and 516 may be positioned suchthat the electrodes 528 a and 528 b are on opposite sides of acontinuous linear or curvilinear lesion. For example, electrode 528 amay be placed within the left atrium and electrode 528 b may be placedon the pulmonary vein side of a pulmonary vein ostium. A pulse ofstimulation energy (about 10 mA) may be applied to viable tissue on oneside of the lesion by the electrode 528 a and the viable tissue on theother side of the lesion may be monitored with the electrode 528 b todetect whether or not there is local excitation from the pulse ofstimulation energy.

Additionally, the surgical system 30 may be used to determine whether ornot a lesion is transmural. Here, the electrodes 528 a and 528 b may beplaced on opposite surfaces of the lesion (e.g. the epicardial andendocardial surfaces, or two epicardial surfaces).

Turning to FIGS. 24C-24H, in those instances in which the exemplarysurgical system 30 includes the exemplary energy transmission andstimulation assembly 524′, the stimulation electrodes 529 a 1/529 a 2and 529 b 1/529 b 2 may be used to test a lesion formed with thecoagulation electrodes 526 a and 526 b without moving the clamp 502. Forexample, after the lesion is formed, a pulse of stimulation energy(here, about 10 mA) may be applied to viable tissue on one side of thelesion by stimulation electrodes 529 a 1/529 a 2, while viable tissue onthe other side of the lesion may be monitored with stimulationelectrodes 529 b 1/529 b 2 to detect the local excitation from the pulseof stimulation energy. The tissue stimulation apparatus 300 will measurethe conduction delay between the delivery of the pulse to the tissue onone side of the lesion and the detection of the local activation on theother side of the lesion. The conduction delay is, as noted above,indicative of the quality of the lesion.

VII. Tissue Stimulation and Sensing Probes

As illustrated for example in FIGS. 25-28, a surgical tissue stimulationand sensing system 40 in accordance with one embodiment of a presentinvention includes a tissue stimulation apparatus 300 and a tissuestimulation and sensing probe 600. The tissue stimulation apparatus 300is described above. The exemplary tissue stimulation and sensing probe600 includes a tissue engagement device 602 that carries a pair ofstimulation electrodes 604 and is supported on the distal end of a shaft606. The electrodes 604 may be used to sense electrical actively inaddition to transmitting stimulation energy.

The specific size and shape of the tissue engagement device 602 will, ofcourse, depend on the intended application, as will the choice ofmaterials. Although the present inventions are not limited to anyparticular sizes, shapes or materials, one exemplary implementation thatis especially well suited for cardiac treatment is described hereafter.The exemplary tissue engagement device 602 cup-shaped and is formed,preferably by molding, from a soft, flexible biocompatible material suchas silicone rubber or urethane. The diameter of the tissue engagementdevice 602 may range from about 2 mm to about 5 mm and is about 2-3 mmin the exemplary embodiment. With respect to the electrical connectionof the stimulation electrodes 604 to the tissue stimulation apparatus300, the stimulation electrodes in the exemplary implementation areconnected to signal lines 608 that extend from the stimulationelectrodes, though a shaft lumen 610, and an opening (not shown) at theproximal end of the shaft 606. The signal lines are connected to theconnectors 302 on the stimulation apparatus 300 in the manner discussedabove.

In the exemplary implementations illustrated in FIGS. 25-32, thestimulation electrodes 604 are essentially the same as the stimulationand sensing electrodes 426 and 428 described above. For example, theelectrodes 604 may be relatively small, low profile devices (e.g. about0.5 mm to 1 mm in diameter and about 0.01 mm thick) that can be formedby coating one of the suitable conductive materials described above ontothe tissue engagement device 602.

Turning to the particulars of the exemplary shaft 606, the shaft in theillustrated embodiment is relatively short and relatively stiff. Morespecifically, the exemplary shaft 606 is about 20 cm to 50 cm in lengthand is formed from a malleable hypotube 612 with an outer tubing 614formed from Pebax® material, polyurethane, or other suitable materials.A typical hypotube would be about 2 mm and 8 mm in diameter. Thestiffness of the shaft 606 allows the physician to firmly place theelectrodes 604 against tissue, while the malleability of the shaftallows the physician to vary the shape of the shaft as desired to suitparticular needs.

The exemplary surgical tissue stimulation and sensing system 40 may beused to, for example, test the quality of lesions formed during a lesionformation procedure in a variety of ways. For example, the physician mayfirst bend the shaft 606 into the appropriate shape to reach to thetarget tissue. The shaft 606 may, of course, also be used in a linearorientation. The tissue engagement device 602 may be placed againsttissue on one side of a lesion and the stimulation electrodes 604 may beused to apply stimulation energy to the tissue. For example, the tissueengagement device 602 may be placed on the pulmonary vein side of apulmonary vein isolation lesion. The stimulation energy may be in theform of a bipolar pacing pulse (e.g. 10 mA). The physician can determinewhether or not a therapeutic lesion (or “complete block”) has beenformed by observing the tissue on the other side of the lesion. If thepacing pulse is able to cross the lesion, the heart will beat faster(e.g. 120 beats/minute). This may be determined by observation or by useof an ECG machine that is monitoring the heart.

Alternatively, the stimulation electrodes 604 may be used to sensetissue within the area defined by a lesion to determine whether heart'snatural stimulation will produce local activation within the tissue areadefined by the lesion. For example, the tissue engagement device 602 maybe placed on the pulmonary vein side of a pulmonary vein isolationlesion. No local activation within the area defined by the lesion isindicative of the formation of a complete excitation block, while localactivation is indicative of a gap in the lesion.

Other methods involve the use of two or more of the tissue stimulationand sensing probes 600. For example, the tissue engagement devices 602of two separate probes may be placed against tissue on opposite sides ofa lesion. The stimulation electrodes 604 of one probe may be used toapply stimulation energy to the tissue, while the stimulation electrodeson the other may be used to sense local activation. This technique maybe used to, amongst other things, test lesions that are formed aroundone or more of the pulmonary veins. Here, the stimulation electrodes 604of one probe may be placed against tissue within the left atrium andstimulation electrodes 604 of another probe may be placed on thepulmonary vein side of a pulmonary vein ostium. A pulse of stimulationenergy (about 10 mA) may be applied to viable tissue on one side of thelesion and the viable tissue on the other side of the lesion may bemonitored to detect the local excitation from the pulse of stimulationenergy.

Turning to FIG. 27A, in an alternative implementation, a tissueengagement device 602′ that is substantially larger than the tissueengagement device 602 (e.g. about 1 cm in diameter) may be provided onthe end of the shaft 606. The tissue engagement device 602′ supports twopairs of stimulation electrodes 604 (i.e. pairs 604 a and 604 b). Eachpair may be operated in bipolar fashion in a manner similar to thatdescribed above with reference to electrode pairs 426 a and 428 a. Forexample, the pairs of stimulation electrodes may the positioned onopposite sides of a continuous linear or curvilinear lesion. A pulse ofstimulation energy (about 10 mA) may be applied to viable tissue on oneside of the lesion by the electrodes in pair 604 a and the viable tissueon the other side of the lesion may be monitored with the electrodes inpair 604 b to detect the local excitation from the pulse of stimulationenergy. As noted above, the conduction delay will be indicative of thequality of the lesion.

There are a number of advantages associated with the exemplary tissuestimulation and sensing probe 600. For example, using the tissuestimulation and sensing probe 600 to place stimulation electrodesagainst tissue is much easier than the conventional method of securingpacing electrodes to tissue, which involves suturing the pacingelectrodes to tissue, especially in those instances where thestimulation electrodes will only be in place for a short time. Thestimulation and sensing probe 600 also makes it much easier to removethe stimulation electrodes 604 from the patient, or move the electrodesto a new tissue location, as compared to pacing electrodes that aresutured to tissue. It should also be noted the stimulation and sensingprobe 600 may be used in a pacing procedure, especially one in which itis desirable to pace at numerous locations within the heart.

Another surgical tissue stimulation and sensing system, which isgenerally represented by reference numeral 50 in FIG. 29 includes atissue stimulation apparatus 300, a suction source 402 and a tissuestimulation and sensing probe 616. The tissue stimulation apparatus 300and a suction source 402 are described above. The exemplary tissuestimulation and sensing probe 616 includes a suction device 618 thatcarries a pair of stimulation electrodes 604 and is supported on thedistal end of a flexible tube 620. The proximal end of the flexible tube620 is connected to a handle 622. The suction device 616 is connected tothe suction source 402 by way of a lumen 624 that extends through theflexible tube 620 and a flexible tube 406 that is connected to theproximal end of the handle 622 by a connector 626 such as, for example,the illustrated Luer connector. When the suction source 402 is actuated,the suction device 602 will fix the stimulation electrodes 604 againstthe target tissue.

The specific size and shape of the suction device 618 will, of course,depend on the intended application, as will the choice of materials.Although the present inventions are not limited to any particular sizes,shapes or materials, one exemplary implementation that is especiallywell suited for cardiac treatment is described hereafter. The suctiondevice 618 is formed, preferably by molding, from a soft, flexiblebiocompatible material such as silicone rubber or urethane. The diameterof the suction device 618 may range from about 2 mm to about 10 mm andis about 2-3 mm in the exemplary embodiment. With respect to theconnection of the stimulation electrodes to the 604 to the tissuestimulation apparatus 300, signal lines 612 extend from the stimulationelectrodes though the lumen 624 and though a pair of openings (notshown) in the handle 622. The flexible tube 620, which may be formedfrom polyurethane, Santoprene® or other suitable materials, ispreferably about 20 cm to about 100 cm in length.

The exemplary surgical tissue stimulation and sensing system 50 may beused to, for example, test the quality of lesions formed during a lesionformation procedure in a variety of ways. For example, the suctiondevice 618 may be secured to tissue on one side of a lesion, eitherbefore or after the lesion is formed. This may be accomplished byplacing the suction device 618 against tissue (typically with a forcepsor other suitable surgical instrument) and then actuating the suctionsource 402. The stimulation electrodes 604 may then be used to applystimulation energy to the tissue. The stimulation energy may be in theform of a bipolar pacing pulse (e.g. 10 mA). The physician can determinewhether or not a therapeutic lesion (or “complete block”) has beenformed by observing the tissue on the other side of the lesion. If thepacing pulse is able to cross the lesion, the heart will beat faster(e.g. 120 beats/minute). This may be determined by observation or by useof an ECG machine that is monitoring the heart. Alternatively, thestimulation electrodes may be used to sense tissue within an isolatedregion in the manner described above in order to determine whether acomplete line of block has been formed.

Other methods involve the use of two or more of the tissue stimulationand sensing probes 616. For example, the suction device 618 of twoseparate probes may be placed against tissue on opposite sides of alesion. The stimulation electrodes 604 of one probe may be used to applystimulation energy to the tissue, while the stimulation electrodes onthe other may be used to sense local activation. This technique may beused to, amongst other things, test lesions that are formed around oneor more of the pulmonary veins. Here, the stimulation electrodes 604 ofone probe may be placed against tissue within the left atrium andstimulation electrodes 604 of another probe may be placed on thepulmonary vein side of a pulmonary vein ostium. A pulse of stimulationenergy (about 10 mA) may be applied to viable tissue on one side of thelesion and the viable tissue on the other side of the lesion may bemonitored to detect the local excitation from the pulse of stimulationenergy.

Turning to FIG. 31A, in an alternative implementation, a suction device618′ that is substantially larger than the suction device 618 (e.g.about 1 cm in diameter) may be provided on the end of the tube 620. Thesuction device 618′ supports two pairs of stimulation electrodes 604(i.e. pairs 604 a and 604 b). Each pair may be operated in bipolarfashion in a manner similar to that described above with reference FIG.27A.

There are a number of advantages associated with the exemplary tissuestimulation probe 616. For example, using suction force to hold thestimulation electrodes 604 in place on the target tissue is much easierthan the conventional method of securing pacing electrodes to tissue,i.e. suturing the pacing electrodes to tissue. The stimulation probe 616also makes it relatively easy to disconnect the electrodes 604 from thetissue, i.e. by simply ending the suction force, so that the electrodesmay be removed from the patient or moved to a new location. Thestimulation and sensing probe 616 may also be used in a pacingprocedure, especially one in which it is desirable to pace at numerouslocations within the heart.

Finally, it should be noted that a single stimulation electrode may beprovided on the sensing probes 600 and 616, and a single stimulationelectrode may be provided in place of each of the electrode pairsillustrated in FIGS. 27A and 31A.

VIII. Self-Anchoring Tissue Stimulation and Sensing Devices

As illustrated for example in FIGS. 33-36, a surgical tissue stimulationand sensing system 60 in accordance with one embodiment of a presentinvention includes a tissue stimulation apparatus 300 and aself-anchoring stimulation and sensing device 700. The tissuestimulation apparatus 300 is described above. The exemplaryself-anchoring stimulation and sensing device 700 includes a pair ofstimulation electrodes 702 that are supported on an anchor 704. Theelectrodes 702 may be used to sense electrical actively in addition totransmitting stimulation energy.

A wide variety of anchors may be employed. The exemplary anchor 704illustrated in FIGS. 33-36 includes a flexible, pre-shaped carrier 706and a pair of tissue piercing members 708. The exemplary carrier 706 hasa pair of end portions 706 a/706 b and an interior portion 706 c. Whenin an unstressed (or relaxed) state, the interior portion 706 c will bein spaced relation to a surface, such as a tissue surface, which the endportions 706 a/706 b are in contact with. The carrier 706 and tissuepiercing members 708 are dimensioned and positioned relative to oneanother such that the carrier will be deflected (and stressed) when thepiercing members are placed into tissue. As a result, the stimulationelectrodes 702 will be forced (or “biased”) against the tissue when thepiercing members 708 engage the tissue. The exemplary anchor 704 will bebent into a configuration that is flat, such that the interior portion706 c engages the tissue, or is close to flat, when the piercing members708 are completely into the tissue.

The exemplary carrier 706 in the illustrated embodiment includes aflexible, pre-shaped spring member 710, which may be rectangular (asshown), circular or any other suitable shape in cross-section, and asoft plastic coating 712. Alternatively, a pre-shaped rubber (such assilicone rubber) carrier may be employed. The carrier 706 will typicallybe about 1 mm to 4 mm wide and about 6 mm to 20 mm long when flattened.The tissue piercing members 708 are malleable structures that aresecured to the carrier 706 with a base 709. With respect to use, thetissue piercing members 708 are held with a clamp during the applicationand removal process. More specifically, a physician may use a clamp(such as the type of clamp used to attach surgical staples) to spreadthe piercing members 708 apart slightly, force the sharpened ends 714into tissue until the carrier 706 is flat or close to flat, and thenurge the piercing member towards one another to secure theself-anchoring stimulation and sensing device 700 to the tissue. Thedevice 700 may be removed by simply spreading the piercing members 708apart slightly with a clamp (such as the type of clamp used to removesurgical staples) and pulling the device away from the tissue.

The exemplary stimulation electrodes 702 may be ring electrodes that areabout 0.5 mm to 2 mm in length and are otherwise similar to thering-shaped stimulation electrodes described above. Alternatively, thestimulation electrodes may be relatively small, low profile devices(e.g. about 0.5 mm to 1 mm in diameter, and about 0.01 mm thick) locatedon the tissue facing side of the carrier 706. Such electrodes may beformed by coating a conductive material onto the carrier 706 usingconventional coating techniques or an IBAD process.

The electrodes are connected by signal lines 716 that extend from thestimulation electrodes 702 and along portions of the carrier 706. Thesignal lines 716 are connected to the connectors 302 on the stimulationapparatus 300 in the manner discussed above. An overcoat 718 may also beprovided.

Another exemplary self-anchoring stimulation and sensing device isgenerally represented by reference numeral 720 in FIGS. 37 and 38. Thedevice illustrated in FIGS. 37 and 38 is substantially similar to thedevice illustrated in FIGS. 33-36 and similar elements are representedby similar reference numerals. Here, however, the exemplary anchor 722includes the flexible, pre-shaped carrier 706 and a rotatable tissuepiercing device 724 that is associated with the interior portion 706 c.The rotatable tissue piercing device 724 has a helical member 726 thatis connected to a knob 728. Rotation of the knob 728 in one directionwill cause the helical member 726 to screw into the tissue. The rotationmay continue until the carrier 706 is flat or close to flat, theinterior portion 706 c is against tissue or close to the tissue, and thestimulation electrodes 702 are forced against the tissue by the carrier.Rotation of the knob 728 in the other direction will unscrew the helicalmember 726 and facilitate removal of the stimulation and sensing device720.

Still another exemplary self-anchoring stimulation and sensing device isgenerally represented by reference numeral 730 in FIGS. 39 and 40. Thedevice illustrated in FIGS. 39 and 40 is substantially similar to thedevices illustrated in FIGS. 33-38 and similar elements are representedby similar reference numerals. Here, however, the exemplary anchor 732does not pierce the tissue. The anchor 732 is, instead, secured to thetissue with a layer of adhesive 734 on the carrier interior portion 706c. Suitable adhesives include cyanoacrylate and thrombin adhesive. Arelease layer 736 may also be provided. During use, the physician canremove the release layer 736, place the stimulation and sensing device730 onto the tissue, and press the interior portion 706 c down until theadhesive 734 contacts tissue, thereby securing the interior portion tothe tissue and forcing the electrodes 702 into close contact with thetissue. The physician will simply peel the stimulation and sensingdevice 730 off when the procedure is complete.

The exemplary surgical tissue stimulation and sensing system 60 may beused to, for example, test the quality of lesions formed during a lesionformation procedure in a variety of ways. For example, one or more ofthe stimulation and sensing devices 700, 720 and 730 may be secured totissue on one side of a lesion, either before or after the lesion isformed. The stimulation electrodes 702 may then be used to applystimulation energy to the tissue. The stimulation energy may be in theform of a bipolar pacing pulse (e.g. 10 mA). The physician can determinewhether or not a therapeutic lesion (or “complete block”) has 0.25 beenformed by observing the tissue on the other side of the lesion. If thepacing pulse is able to cross the lesion, the heart will beat faster(e.g. 120 beats/minute). This may be determined by observation or by useof an ECG machine that is monitoring the heart. Alternatively, thestimulation electrodes may be used to sense tissue within an isolatedregion in the manner described above in order to determine whether acomplete line of block has been formed.

Other methods involve the use of two or more of the stimulation andsensing devices 700, 720 and 730. For example, two separate stimulationand sensing devices 700, 720 or 730 may be placed against tissue onopposite sides of a lesion. The stimulation electrodes 702 on one may beused to apply stimulation energy to the tissue, while the stimulationelectrodes on the other may be used to sense local activation. As notedabove, depending on the type of lesion being tested, the presence orabsence of local activation or the conduction delay will be indicativeof the quality of the lesion.

Although the present inventions have been described in terms of thepreferred embodiments above, numerous modifications and/or additions tothe above-described preferred embodiments would be readily apparent toone skilled in the art. By way of example, but not limitation, each ofthe devices described above may be used to pace prior to lesionformation and each of the methods described above may include pacingprior to lesion formation. It is intended that the scope of the presentinventions extend to all such modifications and/or additions and thatthe scope of the present inventions is limited solely by the claims setforth below.

What is claimed is:
 1. A surgical apparatus, comprising: a clampincluding a first clamp member, a second clamp member, and movementapparatus that moves at least one of the first and second clamp membersrelative to the other of the first and second clamp members such thatthe surgical apparatus is operable between a first state defined by afirst spacing between the first and second clamp members and a secondstate defined by a second spacing between the first and second clampmembers, the first spacing being different from the second spacing; anelectrosurgical power supply and control apparatus; a tissue stimulationapparatus configured to provide pulses of tissue stimulation energyvarying in amplitude over a range of 1 mA to 20 mA; a coagulationelectrode assembly carried by the clamp, and coupleable with theelectrosurgical power supply and control apparatus; and a stimulationelectrode assembly carried by the clamp, and coupleable with the tissuestimulation apparatus.
 2. The surgical apparatus of claim 1, whereineach of the first and second clamp members have a pre-shaped curvature.3. The surgical apparatus of claim 1, further comprising a lockingdevice that locks the clamp so as to provide a spacing between the firstand second clamp members.
 4. The surgical apparatus of claim 1, whereinthe coagulation electrode assembly comprises a first coagulationelectrode coupled with the first clamp member and a second coagulationelectrode coupled with the second clamp member.
 5. The surgicalapparatus of claim 1, wherein the stimulation electrode assemblycomprises a first stimulation electrode coupled with the first clampmember and a second stimulation electrode coupled with the second clampmember.
 6. The surgical apparatus of claim 5, wherein the source ofstimulation energy is switchable between a bipolar mode and a unipolarmode, such that when in the bipolar mode the source of stimulationenergy is operable to transmit stimulation energy to the firststimulation electrode and receive stimulation energy from the secondstimulation electrode, and when in the unipolar mode the source ofstimulation energy is operable to transmit stimulation energy to boththe first stimulation electrode and the second stimulation electrode. 7.The surgical apparatus of claim 1, wherein the coagulation electrodeassembly comprises a flexible coagulation electrode.
 8. A surgicalapparatus, comprising: a clamp including a first clamp member, a secondclamp member, and movement apparatus that moves at least one of thefirst and second clamp members relative to the other of the first andsecond clamp members such that the surgical apparatus is operablebetween a first state defined by a first spacing between the first andsecond clamp members and a second state defined by a second spacingbetween the first and second clamp members, the first spacing beingdifferent from the second spacing; a coagulation electrode assemblycarried by the clamp; an electrosurgical power supply and controlapparatus coupleable with the coagulation electrode assembly; astimulation electrode assembly carried by the clamp and comprising afirst stimulation electrode; and a tissue stimulation apparatuscoupleable with the stimulation electrode assembly, and configured toprovide pulses of tissue stimulation energy varying over a range betweena first amplitude and a second amplitude, wherein the first amplitude issufficient to stimulate viable heart tissue that is no more than about2.8 mm from the stimulation electrode when in contact with the hearttissue, and wherein the second amplitude is sufficient to stimulateviable heart tissue that is no more than about 13.0 mm from thestimulation electrode when contacting the heart tissue.
 9. The surgicalapparatus of claim 8, wherein each of the first and second clamp membershave a pre-shaped curvature.
 10. The surgical apparatus of claim 8,further comprising a locking device that locks the clamp so as toprovide a spacing between the first and second clamp members.
 11. Thesurgical apparatus of claim 8, wherein the coagulation electrodeassembly comprises a first coagulation electrode coupled with the firstclamp member and a second coagulation electrode coupled with the secondclamp member.
 12. The surgical apparatus of claim 8, wherein thestimulation electrode assembly further comprises a second stimulationelectrode, the first stimulation electrode coupled with the first clampmember and the second stimulation electrode coupled with the secondclamp member.
 13. The surgical apparatus of claim 12, wherein the sourceof stimulation energy is switchable between a bipolar mode and aunipolar mode, such that when in the bipolar mode the source ofstimulation energy is operable to transmit stimulation energy to thefirst stimulation electrode and receive stimulation energy from thesecond stimulation electrode, and when in the unipolar mode the sourceof stimulation energy is operable to transmit stimulation energy to boththe first stimulation electrode and the second stimulation electrode.14. The surgical apparatus of claim 8, wherein the coagulation electrodeassembly comprises a flexible coagulation electrode.